Parse int values for WLC_SET_VAR command

Parse value parameter for WLC_SET_VAR if var is of integer type.
Type based on grepping linux driver sources for:
 - brcmf_fil_iovar_int_set
 - brcmf_fil_iovar_int_get
Merge pull request #2 from kanstrup/misc

Parse int values for WLC_SET_VAR command